printf() formatting for hex

ex1) 

http://stackoverflow.com/questions/14733761/printf-formatting-for-hex

int i = 7;
printf("%#010x\n", i);  // gives 0x00000007
printf("0x%08x\n", i);  // gives 0x00000007
printf("%#08x\n", i);   // gives 0x000007

ex2)

void tc38()

{

    printf("%02x\n", 0x00ff);

    printf("%04x\n", 0x00ff);

}

=>

ff

00ff